Calculation of Stator Natural Frequencies of Permanent Magnet Synchronous Motors Considering Complex Boundary Conditions

The accurate calculation and reasonable adjustment of the natural frequencies of the stator are crucial to improve electromagnetic vibration and noise in the electrical machines. The existing calculation methods for the natural frequencies of the stator have a lot of simplifications, which results in low accuracy. In this paper, the stator core is regarded as a ribbed cylindrical shell, the displacement functions of the mid-surface in the cylindrical shell are dispersed as a superposition of orthogonal functions by Gram-Schmidt orthogonalization method, the characteristic equations of natural frequencies of the stator under different boundary conditions are derived based on the energy method, and the natural frequencies including axial and circumferential modal shapes are obtained.